OLED Barrier Ribs and Planarization Layer for Light Extraction
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Solution Overview
Problem
OLED display devices suffer from significant light loss as light passes through multiple layers, leading to reduced transmittance and frontal visibility, with existing solutions like lenses being difficult to control and having long distances that do not effectively improve transmittance.
Innovation Solution
The implementation of a substrate with first and second electrodes, an organic light emitting layer, a thin film encapsulation layer, barrier ribs, and a planarization layer with a higher refractive index, where the barrier ribs have a closed loop shape and are symmetrically disposed to optimize light reflection and emission, and optionally include a scattering layer and color conversion layer to enhance light efficiency and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light passes through multiple layers in OLED display device, then light transmission is achieved, but transmittance is reduced and light is lost
Solution Approach 1:
The patent converts the harmful effect of light loss through multiple layers into a beneficial outcome by using barrier ribs with specific refractive indices to reflect and redirect light that would otherwise be lost. The barrier ribs capture light traveling at various angles and redirect it toward the front surface, transforming energy loss into useful light output.
Solution Approach 2:
The patent changes the refractive index parameter of the barrier ribs to optimize light reflection and redirection. By selecting materials with specific refractive indices (higher than surrounding layers), the barrier ribs effectively control light propagation paths, improving both transmittance and frontal visibility without adding excessive distance or complexity.
2Illumination intensity
If a lens is formed to improve light transmittance, then light direction control is achieved, but curvature control is difficult and distance becomes too long
Solution Approach 1:
Instead of using a single complex lens structure, the patent segments the light control function into multiple barrier ribs distributed across the OLED structure. Each barrier rib is a simple geometric element, but collectively they achieve the light redirection function that would otherwise require a complex lens, simplifying both manufacturing and curvature control.
Solution Approach 2:
The barrier ribs serve as intermediary structures between the OLED layers and the external environment. Rather than directly modifying light with a complex lens, the barrier ribs act as intermediate elements that gradually redirect light paths, achieving the desired optical effect with simpler geometry and shorter distance.
3Productivity
If barrier ribs are added to improve light efficiency, then outgoing light efficiency is improved, but device structure becomes more complex
Solution Approach 1:
The barrier ribs serve multiple functions simultaneously: they provide mechanical support, define pixel boundaries, control light propagation, and enhance light extraction. This multi-functionality allows the structure to improve outgoing light efficiency without requiring additional separate components, thereby limiting the increase in overall device complexity.
Solution Approach 2:
The patent merges the barrier rib structure with existing OLED components such as the encapsulation layers and pixel defining structures. By integrating light control functions into existing structural elements rather than adding completely separate components, the design improves light efficiency while minimizing structural complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly improves outgoing light efficiency and frontal visibility by reflecting and condensing light towards the front surface, optimizing the refractive indices and geometries of the barrier ribs and planarization layer, and further enhancing light emission through the scattering and color conversion layers.
Implementation Method 1
a planarization layer disposed on the thin film encapsulation layer and the plurality of barrier ribs, and having a refractive index higher than that of the plurality of barrier ribs
Implementation Method 2
barrier ribs disposed on the thin film encapsulation layer and overlapping the pixel defining layer between two adjacent ones of the plurality of first electrodes
Implementation Method 3
Holes injected from one of the two electrodes and electrons injected from the other of the two electrodes are combined with each other in the organic light emitting layer to form an exciton. When such excitons fall from an excited state to a ground state, an energy is released to emit light.
Data Source
AI summary
An organic light emitting display device includes a substrate, first electrodes disposed on the substrate, a pixel defining layer disposed on the substrate and exposing at least a part of the first electrodes, a second electrode disposed on the first electrodes and the pixel defining layer, an organic light emitting layer disposed between the first electrodes and the second electrode, a thin film encapsulation layer disposed on the second electrode, barrier ribs disposed on the thin film encapsulation layer, the barrier ribs overlapping the pixel defining layer between two adjacent ones of the first electrodes, and a planarization layer disposed on the thin film encapsulation layer and the barrier ribs, and having a refractive index higher than that of the barrier ribs. Each of the barrier ribs has a closed loop shape that encloses one of the two adjacent ones of the first electrodes in a plan view.